The brain is likely an important reservoir for the human immunodeficiency virus (HIV). It is clear that HIV infects the invading macrophages, resident microglia and astrocytes in the brain. However, the fundamental mechanisms by which the virus resides in these cells for prolonged periods of time is not understood. It also remains unknown if antiretroviral therapy can control viral replication in these cells or have an impact on the viral reservoirs in brain. We thus propose to determine mechanisms involved in maintaining the virus in these cell types post viral entry and determine the effect of antiretroviral therapy on the viral lifecycle in these cells. We hypothesize that establishment of a viral reservoir in brain involves specific antiviral genes which are differentially regulated in macrophages and astrocytes and once the reservoir is established, antiretroviral therapy will have little or no effect on the persistence of the virus in these cells. We will use a combination of in vitro human brain cultures and blood derived macrophages to address the aims below. These studies will compliment those in project #1 which will study viral persistence in macrophages in vivo and ex vivo and projects #2 and 3 that will determine the effect of antiretroviral therapy on brain in vivo. Preliminary data from our laboratory suggests that the Tat protein of HIV regulates the expression of several interferon inducible antiviral genes. We have generated several novel cell lines and viral constructs that will allow us to address these issues related to viral reservoirs in the brain. We thus propose the following specific aims: 1: To determine the role of antiviral protein, promelyocytic leukemia protein (PML) in HIV replication in astrocytes and macrophages. 2. To determine the effect of HIV in astrocytes and macrophages on antiviral genes, interferon stimulated gene-20 (ISG 20) and oligoadenylate synthetase (OAS-1). 3: To determine the effect of CART on HIV replication and persistence in astrocytes and macrophages.